The origin of Stanford prison experiment(Part1)

There were many problems in American prison in the 1960s. Many of these problems were concerned about the brutal attacks by prison guards to prisoners in their care.The reasons of the brutal attacks are mentioned as two possibilities. First possibility is that the people who choose to be the prison guards tend to have aggressive or sadistic personalities. Second possibility is that the behavior of prison guards caused by the social environment of prison that includes the strict power which is fond in their situation. These two possibilities were considered as dispositional and situational explanations.